Fix Ithorian backpacks not visible: add missing appearance table entries

appearance_table.tab had an entry for shared_ith_backpack_s06 (Ithorian
only, :block for all other species) but was missing equivalent entries
for shared_ith_backpack_s01, s03, and s05. Without these entries the
client cannot resolve the correct appearance file for those backpack
variants when worn by an Ithorian, causing them to be invisible.

Appearance filenames taken from the existing entries for the same meshes
used by shared_backpack_s01/s03/s05 in the Ithorian columns.

Fixes #275

Author: nickk02

sku.0/sys.shared/compiled/game/datatables/appearance/appearance_table.tab

@@ -1003,6 +1003,9 @@ shared_ith_skirt_s02	:block	:block	:block	:block	:block	:block	:block	:block	:bl
 shared_ith_skirt_s03	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	appearance/ith_skirt_s03_m.sat	appearance/ith_skirt_s03_f.sat	:block	:block
 shared_ith_vest_s01	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	appearance/ith_vest_s01_m.sat	appearance/ith_vest_s01_f.sat	:block	:block
 shared_ith_vest_s02	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	appearance/ith_vest_s02_m.sat	appearance/ith_vest_s02_f.sat	:block	:block
+shared_ith_backpack_s01	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	appearance/ith_backpack_s01_m.sat	appearance/ith_backpack_s01_f.sat	:block	:block
+shared_ith_backpack_s03	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	appearance/ith_backpack_s03_m.sat	appearance/ith_backpack_s03_f.sat	:block	:block
+shared_ith_backpack_s05	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	appearance/ith_backpack_s05_m.sat	appearance/ith_backpack_s05_f.sat	:block	:block
 shared_ith_backpack_s06	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	appearance/ith_backpack_s06_m.sat	appearance/ith_backpack_s06_f.sat	:block	:block
 shared_ith_belt_s18	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	appearance/ith_belt_s18_m.sat	appearance/ith_belt_s18_f.sat	:block	:block
 shared_ith_belt_s19	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	:block	appearance/ith_belt_s19_m.sat	appearance/ith_belt_s19_f.sat	:block	:block